PROTOBASIDIOMYCETES 425 



XXI. I'KDAR AI'l'LKS AND APPLE RUST 

 Gymnosporangium ma crop us Lk. 



This is one of the most widespread and economically important 

 of this genus. It produces the large cedar apples on Juniperus 

 virginiana (Fig. 207). This fungus occurs practically throughout 



FK;. 207. C,Y.M.\osroK.\.\\;iL-.\i M.H xorrs: CEDAR AITI.K 



the range of the red cedar and its other hosts. The aecidial stage 

 occurs on the apple (Pynis M<ihis) and also on I\rns coroiiaria, 

 and was originally (U-scrilu-d as kirstcliti rymttt (Sclnv.) Thaxtrr. 

 On the leaves SOUK- injury is done to these plants when the 



